The goal of the study is to gain an improved understanding of T cell recognition in murine experimental allergic encephalomyelitis (EAE), which is believed to be a representative model of multiple sclerosis in humans. The studies will be directed towards analysis of a T cell receptor (TCR) derived from the 1934.4 T cell hybridoma. This hybridoma originated from a representative encephalitogenic T cell clone in H-2/u mice. The TCR recognizes the immunodominant N-terminal 11-mer of myelin basic protein and is also cross-reactive with several position 3 analogs of this peptide. The applicant has solved the X-ray structure of the 1934.4 Va domain (Va4.2-Ja40) and used the 14.3d (Vb8.2) beta-chain structure to build a model of the 1934.4 TCR (which contains Vb8.2). She proposes to test these hypotheses: (i) that all 3 CDRs of each V domain and HV4 of the a chain are used in antigen recognition. (ii) that the affinity of the tripartite interaction in this system correlates with antigen responsiveness. (iii) that there are multiple footprints for the wild-type and mutated 1934.4 TCR on different peptide:MHC class II complexes. These hypotheses will be tested by: (i) generating transfectants expressing mutated TCRs and analyzing antigen responsiveness; (ii) plasmon resonance; (iii) analyzing the responsiveness of the 1934.4 TCR transfectants to antigen (peptide) pulsed L cell transfectants expressing mutated I-Au molecules; (iv) solving the X-ray structure of the 1934.4 Va:Vb heterodimer. These studies could lead to improvements in our understanding of autoreactive and cross-reactive T cell recognition in this disease model. More generally, the study has relevance to recognition by class II restricted T cells and to T cell mediated disease.